So I inherited about 30 pairs of men's jeans and was considering using them for creating a rag quilt. I'm thinking that they are made of blue denim and are a fairly large size, but worry that I should just go buy denim. Thoughts? Advice?

Old jeans have been used for many years for quilts. They are absolutely the very best for picnic quilts, for kids who love to play indians and make tipis with them, and they will last for years and years.
They WILL be heavy, don't need much if any batting, but if you live in a cold country then you can make a good one that kids and grownups will love for the warmth. And dogs and cats can sleep on them too, with not much chance of runs from sharp claws.

Ohhhhhh....yes! And boy are they great. I remember in a class I was teaching, one of the ladies had made one. She had collected jeans from her family. They had wear marks and stains and paint splatters, well you get the idea. Any way, what a precious memory quilt. The members of her family, as she told the history of this quilt, laughed and cryed and told stories.....Well it was a great memory for me and I'm sure for all that attended my class that day.

I made one for my neice, using her father's jeans after he passed away. I used flannel on the back and the denim on the front, and used muslin as the batting because it was already heavy. It was a queen size ninepatch. I had made it about eight years ago, and it is still going strong.

thats how most denim quilts are made- cut up jeans- been making them that way for 30+ years...no reason to buy new denim (which is expensive) for a raggy quilt- used jeans are soft- nice to work with (new denim is stiff-and not so nice to work with) they fray wonderfully- and everyone will love the quilts made with them-teemed with flannel you have the softest, warmest coziest quilt going :)

I have made rag quilts from recycled jeans and paired with flannel make great rag quilts! Don't spend the money on new denim. Cheaper to use old jeans and the quilts have so much more character with the different denim fabrics.